Novel oxide materials and synthesis by fluoride/chloride anion promoted exfoliation

ABSTRACT

The present invention is directed to the synthesis of novel delaminated layered zeolite precursor materials prepared by fluoride/chloride anion-promoted exfoliation. The method comprises, for example, using a combination of fluoride and chloride anions at a mild pH in aqueous solution to affect delamination of a layered zeolite precursor. The method can also comprise using a combination of fluoride and chloride anions in a non-aqueous solution comprising an organic solvent. The method may be used in conjunction with either acidification or sonication, or both. The resulting delaminated zeolite precursors are then isolated. Precursors that are then isolated lack amorphous silica content. The UCB- 1  product is an example of such a novel oxide material and is obtained in yields in excess of  90 % without the need for sonication.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.13/161,091, filed Jun. 11, 2011, which claims benefit under 35 USC 119of Provisional Application 61/421,906 filed Dec. 10, 2010, the contentsof both documents incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Provided are new oxide materials consisting of delaminated layeredzeolite precursors and a method for synthesizing the materials undermild conditions. More specifically, provided is the synthesis ofdelaminated layered zeolite precursor materials such as UCB-1 to UCB-6by fluoride/chloride anion-promoted exfoliation.

2. Description of the Related Art

The emergence of a new class of catalysts consisting of delaminatedlayered zeolite precursors expands the range of reactions that zeolitescan catalyze by providing access for larger reactant molecules. ITQ-2 inparticular represents the first example of such a material, and consistsof micropores derived from the zeolite precursor material, MCM-22(P),which are imbedded within thin and accessible sheets. See, for example,U.S. Pat. No. 6,231,751. These micropores enable shape-selectivecatalysis. Other delaminated zeolite materials include ITQ-6 synthesizedby delamination of PREFER, and ITQ-18, synthesized by delamination ofNu-6(1). See, for example, Corma et al., “Aromatics Alkylation”, U.S.Pat. No. 6,855,855; “New Aluminosilicate and Titanosilicate DelaminatedMaterials Active for Acid Catalysis, and Oxidation Reactions Using H₂O₂”, J. Am. Chem. Soc., 2000, vol. 122, pp. 2804-2809; and Corma et al.,“ITQ-18 a new delaminated stable zeolite”, Chem. Commun., 2001, pp.2642-2643.

The synthesis of ITQ-2 and other delaminated layered zeolite precursorshas to-date required a high pH medium during precursor materialswelling, typically in the pH range of 13.5 - 13.8. Based on the highsolubility of silica in such basic aqueous solution, proof of partialamorphization of the zeolite precursor layers during delamination isevident via transmission electron microscopy (See Lercher et al.,“Chemical and structural aspects of the transformation of the MCM-22precursor into ITQ-2”, Studies in Surface Science and Catalysis, 142,pp. 69-76) and clearly identifiable Si(OH)₂ resonances, which must bedue to amorphous silica, in the ²⁹Si MAS NMR spectrum of ITQ-2 (See FIG.4 in Corma et al., “Characterization and Catalytic Activity of MCM-22and MCM-56 Compared with ITQ-2”, Journal of Catalysis 2000, 191,218-224.) This has motivated the search for milder conditions fordelamination. While there has been notable success in decreasing thetemperature from 353 K (80° C.) to room temperature during swelling, ithas been impossible to achieve delamination under these milderconditions, since the material reverts back to the zeolite precursorafter acidification of the swollen sample. A delaminated layered zeoliteprecursor material does not revert back to the layered zeolite precursorafter acidification, and does not revert back to the calcined form ofthe layered zeolite precursor after calcination.

It would therefore be of great value to the industry if a synthesis fora new catalyst material of the class of delaminated layered zeoliteprecursors is discovered which involves milder conditions, particularlypH. Furthermore, it would be extremely cost effective to circumvent theneed for sonication, if possible, when synthesizing a delaminatedlayered zeolite precursor material, since performing sonicationoperations industrially is known to oftentimes be prohibitivelyexpensive. Also important is the successful preparation of the oxidematerial via delamination without the material either reverting back tothe layered zeolite precursor after acidification or reverting back tothe calcined form of the layered zeolite precursor after calcination.

It would also be of great value to the industry if a synthesis for a newcatalyst material of the class of delaminated layered zeolite precursorsis discovered which is effective yet flexible in the conditions whichcan be used for preparing such catalyst materials. An objective of thepresent invention is to provide a flexible process insofar as it can beused at milder pH values, either in organic solvents or in aqueoussolution, and either with or without sonication. This flexibility inprocess conditions is not possible to achieve with the prior art.

SUMMARY OF THE INVENTION

Provided are novel delaminated zeolite precursor materials prepared byfluoride/chlorine anion-promoted exfoliation. The oxide materialprepared by at least partial delamination of a layered zeolite precursoris essentially devoid of an amorphous silica phase. This is achievedthrough the use of chloride and fluoride anion exfoliation. Theavoidance of the amorphous phase in the oxide materials of the presentinvention also preserves more integrity of the two-dimensional zeolitelayers, as characterized, for example, by a more intense sharp peak inthe 20-30 20/degrees range of their X-ray diffraction patterns comparedto prior art delaminated layered zeolite materials such as ITQ-2, lackof resonances attributable to Si(OH)₂—Q² silicon—via ²⁹Si MAS NMRspectroscopy, and lack of amorphous phase via transmission electronmicroscopy.

In one embodiment, the method of preparing the delaminated layeredzeolite precursor material comprises preparing an aqueous mixture ofchloride and fluoride anions with a layered zeolite precursor materialto be delaminated. The aqueous mixture is maintained at a pH of 12 orless, e.g., around 9, generally at a temperature in the range of about5-150° C. to effect the desired delamination. An oxide material such asUCB-1 is then recovered after acidification and centrifugation, and canbe obtained in yields exceeding 90 wt. %. The use of milder conditions,especially pH, during the synthesis using an aqueous solutionsubstantially avoids the creation of an amorphous phase, whereas theobviation of sonication is a practical cost-effective advantage of thesynthesis.

In another embodiment, the method of preparing the delaminated layeredzeolite precursor comprises preparing a non-aqueous mixture of chlorideand fluoride anions with a layered zeolite material to be delaminated.The mixture is heated at a temperature in the range of about 5-150° C.to effect the desired delamination. The non-aqueous mixture generallycomprises an organic solvent such as dimethyl formamide (DMF). An oxidematerial such as UCB-2 is then recovered after acification andfiltration, or, alternatively, an oxide material such as UCB-3 is thenrecovered after deionized water wash and filtration.

In another embodiment, the method of preparing the delaminated layeredzeolite precursor comprises preparing a non-aqueous mixture, e.g., usingan organic solvent such as dimethyl formamide, of chloride and fluorideanions with a layered zeolite material to be delaminated. After heatingthe mixture at a temperature in the range of from about 5-150° C. toaffect the desired delamination, the mixture is subjected to sonicationand filtration. An oxide material such as UCB-4, UCB-5 or UCB-6 is thenrecovered.

Among other factors, the present process permits one to prepare adelaminated zeolite precursor material by using a combination ofchloride and fluoride anions, e.g., from a combination of alkylammoniumfluoride and chloride surfactants. The process avoids the creation of anamorphous silica phase. When using an aqueous mixture, the processpermits milder conditions of pH than have heretofore been possible. ThepH can be less than 12, and essentially avoids the creation of anamorphous silica phase. For example, in an aqueous solution of pH 12 orless, delamination of a layered zeolite precursor material is achievedto provide a stable product, e.g., UCB-1. The process can also beperformed in a non-aqueous mixture, with which sonication can be used ornot used. Stable products such as UCB-2, UCB-3, UCB-4, UCB-5 and UCB-6are achieved. The products themselves are novel as they demonstrateunique morphology and high structural integrity.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING

FIG. 1 shows a powder x-ray diffraction pattern characterizing MCM-22(P)(Si:Al ratio of 50) delaminated in the absence of chloride;

FIG. 2 shows a powder x-ray diffraction pattern characterizing MCM-22(P)(Si:Al ratio of 50) delaminated in the absence of fluoride;

FIG. 3 is a ¹⁹F MAS NMR spectrum characterizing as-made UCB-1;

FIG. 4 shows a powder x-ray diffraction pattern characterizing MCM-22after treatment under the same conditions used to synthesize UCB-1

FIG. 5 shows a powder x-ray diffraction pattern characterizing MCM-22after treatment under the same conditions used to synthesize ITQ-2zeolite.

FIG. 6 shows ²⁹Si MAS NMR spectra characterizing (A) MCM-22(P), (B)as-made ITQ-2; and (C) as-made UCB-1.

FIG. 7 shows powder x-ray diffraction patterns characterization (A)MCM-22(P); (B) as-made ITQ-2 zeolite; and (C) as-made UCB-1.

FIG. 8 shows N₂ adsorption isotherms characterizing the followingmaterials: (o) MCM-22 zeolite in the semi-logarithmic scale, (▴) ITQ-2zeolite, () UCB-1, (x) USY zeolite, and (+) TON zeolite. (The insetshows the data using linear scale.)

FIG. 9 shows cumulative pore volumes characterizing the followingsamples: (1) ITQ-2 zeolite; (2) MCM-22 zeolite; (3) UCB-1.

FIG. 10 are TEM images characterizing (A) and (B) MCM-22(P) and (C) and(D) UCB-1.

FIG. 11 shows powder X-ray diffraction patterns characterizing (A)MCM-22 (Si/Al ratio=20) and (B) the sample delaminated by thefluoride/chloride assisted method of the present process.

FIG. 12 shows the powder X-ray diffraction patterns characterizing (A)ERB-1 and (B) the delaminated product after delamination by thefluoride/chloride method of the present process.

FIG. 13 is a TEM image characterizing as-made UCB-1, with the arrowsindicating single-layers.

FIGS. 14 and 15 show N₂ adsorption isotherms and an indication of poresize.

FIG. 16 shows a scanning electron microscopy image characterizingPREFER.

FIG. 17 shows solid-state ²⁷Al MAS NMR spectra characterizing as-madeUCB-2.

FIG. 18 shows powder XRD patterns characterizing the followingmaterials: (a) swollen PREFER in DMF; (b) acidified PREFER; (c) materialformed by swelling the acidified PREFER.

FIG. 19 shows powder XRD patterns characterizing (a) PREFER and (b)as-made UCB-3.

FIG. 20 shows argon gas adsorption characterizing () calcined PREFER(ferrierite), and (g) calcined UCB-3 in a semi-logarithmic scale. Theinset shows the same data in a linear scale.

FIG. 21 shows powder XRD patterns characterizing (a) PREFER and (b)as-made UCB-4.

FIG. 22 shows argon gas adsorption isotherms characterizing () calcinedPREFER (ferrierite), and (▪) calcined UCB-4 in a semi-logarithmic scale.The inset shows the same data in a linear scale. The data for calcinedPREFER is shown as a comparison.

FIG. 23 shows powder XRD patterns characterizing (a) as-made Al-SSZ-70and (b) as-made UCB-5.

FIG. 24 shows argon gas adsorption isotherms characterizing () calcinedAl-SSZ-70 and (▴) calcined UCB-5 in a semi-logarithmic scale. The insetshows the same data in a linear scale.

FIG. 25 shows powder XRD patterns characterizing (a) as-made B-SSZ-70and (b) as-made UCB-6.

FIG. 26 shows argon gas adsorption characterizing (A) calcined B-SSZ-70and () calcined UCB-6 in a semi-logarithmic scale. The inset shows thesame data in a linear scale.

FIG. 27 shows chemisorbed amounts of base molecules onto acid sites incalcined material UCB-1.

DETAILED DESCRIPTION OF THE INVENTION

The present method involves halide anion delamination of a layeredzeolite precursor material to provide a novel oxide material. An aqueousmixture or an organic solvent mixture of chloride and fluoride anions isused in affecting the delamination. Bromide anion can also be present.The mixtures are maintained at a temperature in the range of from 5-150°C. for a length of time sufficient to effect the desired delamination,e.g., for 30 minutes to one month. The mixture can then be subjected tosonication, or the process can be completed in the absence ofsonication. The oxide product is recovered, often using acidificationand/or centrifugation. The recovered oxide products recovered by thepresent halide anion delamination process are novel oxide productshaving unique morphology and high structural integrity. The presentprocess allows one to prepare a delaminated layered zeolite precursormaterial efficiently and under milder conditions than has heretoforebeen known. The synthesis substantially avoids the creation of anamorphous phase, and can circumvent the need for sonication.

A zeolite is a crystalline three-dimensional assembly of tetrahedralatoms, each of which is surrounded by four oxygen atoms as ligands, soas to form TO₄ units where T represents a tetrahedral atom and can be,but is not limited to, silicon, germanium, vanadium, titanium, tin,aluminum, boron, iron, chromium, gallium, cerium, lanthanum, samarium,phosphorous, and a mixture thereof These TO₄ units are interconnectedthrough their corners. Zeolites can be but are not limited toaluminosilicates, aluminophosphates, heteroatom-substituted materials. Alayered zeolite precursor material consists of two-dimensional zeoliticsheets that are interconnected via either non-covalent (e.g., hydrogenbonding) and/or covalent bonds, which when calcined lead to athree-dimensional zeolite.

When using an aqueous mixture, an aqueous mixture of chloride andfluoride anions, e.g., alkylammoniumhalides, and the layered zeoliteprecursor, the novel oxide product is prepared at a pH less than 12,e.g., about 9, and maintained at a temperature in the range of 5-150° C.for a length of time sufficient to effect the desired delamination. Theoxide product is then recovered, e.g., by acidification to a pH of about2 followed by centrifugation.

When instead using a non-aqueous mixture of chloride and fluorideanions, i.e., a mixture comprising an organic solvent, the mixture isalso maintained at a temperature in the range of from 5-150° C. toeffect desired delamination. The organic solvent can be any suitableorganic solvent, which swells the starting material such as dimethylformamide (DMF). The delaminated product can then be recovered from themixture. Generally, acidification is used to recover the product.Sonication prior to recovery need not be employed, but sonication can beemployed in the process if desired.

The oxide product obtained can comprise oxides of the formula XO₂ andY₂O₃, wherein X represents a tetravalent element and Y represents atrivalent element, with the atomic ratio of X to Y being greater than 3.In one embodiment, X is silicon, germanium, vanadium, titanium, tin, ora mixture thereof, and Y is selected from the group consisting ofaluminum, boron, iron, chromium, titanium, gallium, cerium, lanthanum,samarium, and a mixture thereof See “Framework-substituted lanthanideMCM-22 zeolite: synthesis and characterization”, J. Am. Chem. Soc.,2010, 132, pp. 17989-17991 for examples of the latter three. In anotherembodiment, X is silicon and Y is aluminum. The atomic ratio of X to Yis also often less than 200, or less than 100. In yet another alternateembodiment, the oxide product may contain pentavalent phosphorous aswell as the elements defined above (e.g., as in an aluminophosphatematerial).

The layered zeolite precursors to be delaminated in accordance with thepresent process can be any layered zeolite material. The ultimateproduct will depend upon the starting material and the particularprocess steps used in the synthesis. Examples of suitable layeredzeolite precursor materials include MCM-22 (P), SSZ-25, ERB-1, PREFER,SSZ-70 (e.g., Al-SSZ-70 or B-SSZ-70) and Nu-6 (1). When MCM-22 (P) isused, the novel oxide product UCB-1 is obtained.

The chloride and fluoride anions can be obtained from any source of theanions. Any compound which will provide the anions in aqueous solutioncan be used. The cation is not important. Providing the fluoride andchloride anions is important. The cations can be any cation, with theuse of alkylammonium cations being suitable in one embodiment. The alkylgroup of such a cation can be any length, and in one embodiment rangesfrom 1-20 carbons. Tetrabutylammonium cations in particular have beenfound useful. The molar ratio of chloride to fluoride anions can be 100or less, generally from 100:1 to 1:100. In one embodiment, the ratio canrange from 50:1 to 1:50.

It is the combination of the fluoride and chloride anions which has beendiscovered to be important. When delamination was attempted withfluoride without chloride, the PXRD pattern of the dried product clearlyshowed retention of strong 001 and 002 peaks, indicating that efficientdelamination requires chloride anions as well. See FIG. 1. On the otherhand, fluoride is also a necessary component because delamination usingonly chloride in the absence of fluoride results in partialdelamination, as shown in FIG. 2. The ¹⁹F NMR spectrum characterizingthe as-made UCB-1, shown in FIG. 3, shows a resonance at −128.6 ppm,which is attributable to SiF₆ ². This is consistent with coordination offluoride to Si atoms in the interlayer to facilitate delamination.

The pH used in the present synthesis when an aqueous mixture is used islower than that generally used in delamination synthesis. The pH isgenerally 12 or less, but can be any pH which does not amorphasize thesilica in the zeolite to create an amorphous silica phase. A pH of 12 orless generally accomplishes this task and thereby allows one to obtain adelaminated layered zeolite precursor material substantially without anamorphous phase. In another embodiment, the pH is 11 or less, and even10 or less, with a pH of about 9 or less also being quite advantageous.A pH of approximately 9 is typically used in fluoride-mediated synthesisof zeolites—which otherwise require high pH (above 12). See Corma etal., “Synthesis in fluoride media and characterisation ofaluminosilicate zeolite beta”, Journal of Materials Chemistry, 1998, 8,pp. 2137-2145.

The temperature used in the process for either the aqueous ornon-aqueous mixture can range widely. In general a temperature for theaqueous solution of from 5-150° C. is suitable. In another embodiment,the temperature can range from 50-100° C.

The length of time the zeolite is allowed to swell, and delaminate, inthe aqueous solution can vary greatly. Generally, the time can vary from30 minutes to one month. In one embodiment, the time ranges from 2 hoursto 50 hours. In another embodiment, the time can range from 5 to 20hours prior to collection of the product.

The mild conditions used for the present synthesis are demonstrated incomparison with those used to synthesize ITQ-2, by applying bothtreatments to calcined zeolite MCM-22. The treatment of calcined MCM-22under UCB-1, (the present) synthesis conditions, leads to a product withan intense powder pattern resembling parent MCM-22, see FIG. 4. However,treatment of calcined MCM-22 under ITQ-2 synthesis conditions leads todestruction of zeolite crystallinity as evidenced by intense amorphousfeatures and decreased overall peak intensity in the PXRD pattern, seeFIG. 5. This demonstrates via direct comparison the gentler nature ofthe UCB-1 versus ITQ-2 synthetic conditions on the aluminosilicateframework.

²⁹Si MAS NMR spectroscopy in FIG. 6 further compares as-made materialsUCB-1 and ITQ-2. Shown are NMR data characterizing (A) MCM-22(P); (B)as-made ITQ-2, and (C) as-made UCB-1. The well-resolved resonances inthe Q⁴ region (−105<δ<−120 ppm) and the entire absence of Q² resonancesfor the spectrum in FIG. C relative to FIG. B means a higher degree ofstructural order for material UCB-1 versus ITQ-2. The observed breadthof the Q⁴ region and appearance of Q² resonances (≈−91 ppm) in Figure Bfor as-made ITQ-2 are consistent with amorphization of the zeoliteprecursor material as a result of the high pH conditions used duringdelamination. The Q² resonances described above for ITQ-2 are similar tothose described by Corma et al., “Characterization and CatalyticActivity of MCM-22 and MCM-56 Compared with ITQ-2”, Journal of Catalysis2000, 191, 218-224.

The oxide product is collected using conventional techniques such ascentrifugation. An acid treatment step can be employed prior tocentrifugation, and may be conveniently conducted by contacting theswollen or partially delaminated layered zeolite precursor material witha strong acid, e.g., a mineral acid such as hydrochloric acid or nitricacid, at low pH, e.g., pH 2. Collection of the resulting oxide materialproduct can be performed by centrifugation.

The oxide product obtained by the present process, as noted previously,depends on the starting material. Essentially any layered zeolitematerial can be used as a precursor in the present delamination process.In an embodiment, MCM-22 can be used as the precursor layered zeolitematerial, hereinafter designated as MCM-22(P). Using the presetfluoride/chloride anion promoted exfoliation procedure on MCM-22(P)results in a novel UCB-1 product. Characterization of UCB-1 product bypowder x-ray diffraction, transmission electron microscopy, and nitrogenphysiorption at 77K (-194° C.) indicates the same degree of delaminationas for previously reported ITQ-2. Unlike ITQ-2, however, the synthesisof which requires a pH of greater than 13.5 and sonication in order toachieve exfoliation, UCB-1 is comprised of a higher degree of structuralintegrity and no detectable formation of amorphous silica phase.

Powder X-ray diffraction patterns (PXRD) characterizing (A) MCM-22 (P),(B) ITQ-2 zeolite, and (C) new material UCB-1 are shown in FIG. 7. Thepowder X-ray diffraction pattern characterizing the synthesized MCM-22(P) (FIG. 7, pattern A) matches the literature data, showing the 001 and002 diffraction peaks at 3.3 and 6.7° , respectively. These peaksrepresent the lamellar structure of MCM-22 (P). Delamination of MCM-22(P) by the method described in U.S. Pat. No. 6,231,751 leads to asignificant decrease of all peaks characteristic of lamellar structureof MCM-22 (P) (FIG. 7, pattern B), in agreement with the literatureresults for characterizing ITQ-2 zeolite.

The PXRD of the dried UCB-1 product demonstrates a powder patternsimilar to that previously reported for ITQ-2 zeolite. The pattern atFIG. 7C is characteristic of UCB-1. The 001 and 002 peaks aresignificantly diminished in intensity; however, the 310 peak has astronger intensity than for material ITQ-2. This suggests a greaterdegree of long-range order in the direction parallel to the sheet forthe material synthesized by the present fluoride/chloride delaminationmethod. For the present oxide materials, such as UCB-1, the relativeintensity ratio of the local maximum of X-ray diffraction peak in therange of 6-10 20/degrees to that of 20-30 2θ/degrees can be 0.50 orless.

Nitrogen physisorption isotherms at 77K (−194° C.) of calcined materialsUCB-1 and ITQ-2, a well as calcined zeolites MCM-22, TON, andultrastable HY (USY) are shown in FIG. B. The latter three are includedas controls to elucidate where in the isotherm rings of a certain sizeact to physisorb nitrogen. As a reference point, calcined zeolite MCM-22consists of two independent 10 membered-ring (MR) pore channels and 12MR supercages, with one of the 10 MR pore channel systems runningthrough intralayers and the other through interlayers. Therefore, thedelamination of MCM-22 (P) and its subsequent calcination is expected toform a material that retains 10 MR pore channels within each layer,while the other 10 MR pore channel is expected to be significantlyreduced relative to calcined MCM-22 zeolite. These expectations areindeed supported by a comparison of N₂ physisorption data for calcinedMCM-22 and ITQ-2 in FIG. 8. These data demonstrate that at a relativepressure of approximately 10⁻⁷<P/P_(o)<10⁻⁴, the total uptake ofnitrogen into ITQ-2 is lower than that for MCM-22. Calcined zeolites TONand USY are used to further elucidate these differences. Zeolite TONconsists of only 10 MR channels and shows pore filling of these channelsstarting at a relative pressure P/P_(o) of 10⁻⁷. Zeolite USY consists of12 MR windows and large (˜13 Å) supercages, and shows pore filling ofthese pores at a relative pressure in the range of 10⁻⁵<P/P_(o)<10⁻⁴.The isotherm for UCB-1 in FIG. 8 essentially overlaps the isotherm forITQ-2 in the region 10⁻⁷<P/P_(o)<10⁻⁴, which indicates that bothmaterials have similar amounts of 10 MR and 12 MR pores. This requiresthat the degree of delamination for both materials is similar. However,the significantly diminished uptake of UCB-1 for relative pressuresP/P_(o) greater than 10⁻⁴ means that ITQ-2 consists of larger microporesand mesopores, which are absent in UCB-1. Because of delamination, UCB-1has a larger pore volume of large pores than MCM-22 as shown in Table 1below (0.36 cm³/g for UCB-1 vs. 0.22 cm³/g for MCM-22). However, ITQ-2has a significantly larger volume than UCB-1 (0.67 cm³/g vs. 0.36 cm³/g)because of mesopore formation by amorphization. See, FIGS. 14 and 15,which show the N₂ adsorption isotherms with an indication of pore size.

TABLE 1 Pore volume of MCM-22, UCB-1, and ITQ-2 determined from N₂ gasadsorption data range of relative pore volume, cm³/g pressure porediameter MCM-22 UCB-1 ITQ-2 P/P₀ < 10⁻⁵  ≈5 Å 0.11 0.08 0.08 10⁻⁵ < P/P₀< 10⁻⁴ ≈10 Å 0.04 0.03 0.03 10⁻⁴ < P/P₀ < 1.0 large pores includ- 0.220.36 0.67 ing mesopore and macropore

Mesoporosity in ITQ-2 is also evident via TEM and presumably arises dueto the previously postulated amorphization of the zeolitic structureunder the high pH conditions of the conventional synthesis method. Thepreservation of the layered structure of MCM-22 (P) within UCB-1 isevident in the large degree of macroporosity via mercury porosimetry,see FIG. 9, which is significantly smaller in ITQ-2, though bothmaterials are synthesized from the same layered zeolite precursor. Theaverage diameter of macroporosity in UCB-1 of 350 nm correlates wellwith the 0.5-1 μm microcrystalline diameter of the MCM-22 (P) used inthe synthesis of UCB-I. TEM of UCB-1 demonstrates this macroporosity,which is formed between stacks of sheets, and shows the absence ofmesoporosity that is evident in ITQ-2. These results in turn suggest thecomplete preservation of layers during delamination using the presentfluoride/chloride anion-promoted method.

The MCM-22 precursor may be prepared by methods known in the art, e.g.,from a reaction mixture containing an oxide of a tetravalent element(X), e.g., silicon, an oxide of a trivalent element (Y), e.g., aluminum,an organic directing agent (organic template), water and, optionally,sources of alkali or alkaline earth metal (M), e.g., sodium or potassiumcation.

Examples of organic templates that may be used include heterocyclicimines (e.g., hexamethyleneimine, 1,4-diazacycloheptane andazacyclooctane), cycloaklyl amines (e.g., aminocyclopentane,aminocyclohexane and aminocycloheptane), adamantane quarternary ammoniumions (e.g., N,N,N-trimethyl-1-adamantanammonium ions andN,N,N-trimethyl-2-adamantanammonium ions), and mixtures ofN,N,N-trimethyl-1-adamantanammonium ions orN,N,N-trimethyl-2-adamantanammonium ions with either hexamethyleneimineor dipropylamine

The reaction mixture is allowed to crystallize at a temperature in therange from 80 to 225° C. for a period of 1 to 60 days. The crystals thatform are separated from the reaction mixture, washed thoroughly withwater and dried to yield the MCM-22 precursor.

In one embodiment, delamination of MCM-22 (P) by the present method canbe conducted using an aqueous mixture of cetyltrimethylammonium bromide,tetrabutylammonium fluoride, and tetrabutylammonium chloride at pH 9 at353 K for 16 h, which are the same temperature and duration generallyused in conventional high-pH delamination methods. After acidificationof the slurry to pH 2, the delaminated zeolite precursor UCB-1 iscollected by centrifugation.

TEM images of MCM-22 (P) show lamellar assemblies consisting ofrectilinear sheets, see FIGS. 10A and 10B. TEM images of UCB-1, however,clearly show curved layers (FIGS. 10C and 10D) which lack long-rangeorder, as well as single layers of 2.5 nm thickness (FIG. 13).

While the results have generally been demonstrated by using a MCM-22 (P)with a Si:Al ratio of 50, similar degrees of delamination via PXRD havebeen achieved on materials having a Si:Al ratio of 20. This data isshown in FIG. 11. This has been performed using similar conditions tothose reported here, except that a 3 h rather than 16 h swelling time isimplemented.

The method used to synthesize UCB-1 can also be used to delaminatelayered zeolite precursor materials containing boron. This has neverbeen reported using the conventional method based on high pH presumablybecause it leads to degradation of the borosilicate framework. Forexample, as-made ERB-1 zeolite, which contains boron instead ofaluminum, can essentially be delaminated by the present method asindicated by significantly decreased 001 (3.4≈26 Å) and 002 (6.8°≈13 Å)peaks of the sample used in the present method. See FIG. 12, pattern Bis the product and pattern A is the ERB-1 starting sample.

In summary, the present fluoride/chloride method successfullydelaminates MCM-22 (P) at a pH of 9 in aqueous solution. The method isalso able to successfully delaminate lower Si:Al ratio precursors aswell as boron-containing layered zeolite precursors. As such, itpresents the mildest known method for the delamination of layeredzeolite precursor materials. The present method can readily begeneralized to materials with varying silicon to aluminum ratios as wellas a range of layered zeolite precursors.

Novel oxide products UCB-2, UCB-3, UCB-4, UCB-5 and UCB-6 can also beprepared using the present halide anion delamination process. Thestarting material for preparing the products is generally a layeredzeolite precursor consisting of either PREFER or an SSZ-70, i.e., eitherAl-SSZ-70 or B-SSZ-70. The synthesis of these oxide products involvesthe use of a non-aqueous solution comprising an organic solvent. DMF issuch a suitable solvent. For example, UCB-2, which is comprised ofdelaminated PREFER, is a precursor to ferrierite zeolite that contains 8and 10 MR microchannels. The process involves the present process ofhalide anion delamination, and uses a non-aqueous solution fordelamination. DMF has been found to be suitable as the organic solventfor the process.

Preparation of all of the foregoing products are exemplified in thefollowing examples. The zeolite products can be used as catalysts inorganic conversion processes such as catalytic cracking or alkylationreactions. The zeolite materials can be used alone, or with othercatalysts, and can be supported or used in bulk. They can also be usedas a support for large catalysts that would otherwise be unable topenetrate the interior microporosity of a three-dimensional zeoliticmaterial.

Overall, the present process is advantageously flexible insofar as itcan be used at milder pH values, either in organic solvents or inaqueous solution, and either with or without sonication. Suchflexibility is not possible with prior art processes.

The following examples are provided to further illustrate the presentmaterials and synthesis. The examples are meant to be illustrative, andnot limiting.

EXAMPLE 1

Materials. All reagents used in the zeolite synthesis and delaminationwere of reagents grade quality and used as received. USY zeolite used inN₂ gas physisorption was received from Zeolyst International (CBV760,Si/Al ratio of 60). TON zeolite was synthesized at Chevron EnergyTechnology Company.

Synthesis of MCM-22 (P). The zeolite was synthesized by the literaturemethod. Fumed silica (Sigma Aldrich, 3.54 g) was added to an aqueoussolution containing sodium hydroxide (EMD Chemicals, 97%, 0.372 g),hexamethyleneimine (Sigma Aldrich, 99%, 2.87 g), and sodium aluminate(Riedel-de Haen, 0.108 g) in deionized water (46.6 g) under vigorouslystirring. After stirring the mixture for 6 h, the gel was divided intofour portions and each portion was loaded into a Teflon-lined Parrreactor (23 mL). Each reactor was tightly sealed and heated in aconvection oven at 408 K for 11 days with tumbling of the reactor. After11 days of heating, the reactors were cooled down to room temperature,and the product was separated by centrifuge. The separated product waswashed with deionized water thoroughly, and finally dried at 313 Kovernight.

The powder X-ray diffraction (PXRD) pattern characterizing thesynthesized MCM-22 (P) FIG. 7, pattern A, matches the literature data,showing the 001 and 002 diffraction peaks at 3.3 (˜27 Å) and 6.7 (−13Å), respectively. These peaks represent the lamellar structure of MCM-22(P).

Delamination of MCM-22 (P) by the Conventional Method (Synthesis ofITQ-2 Zeolite). MCM-22 (P) that had been prepared in the precedingsection was delaminated by the literature method. Typically, an aqueousslurry of MCM-22 (P) (3.00 g, 20 wt % solid) was mixed withcetyltrimethylammonium bromide (Sigma Aldrich, ˜98%, 3.38 g),tetrapropylammonium hydroxide solution (Alfa Aesar, 40 wt %, 3.67 g),and the mixture was heated at 353 K (80° C.) for 16 hours. After 16hours of heating, the mixture was cooled down to room temperature, andsubjected to sonication for 1 hour. The pH of the slurry was adjusted to2 by adding concentrated HCI aqueous solution, upon which the solutionwas centrifuged to separate the product. Finally, the product was driedat 313 K (40° C.) overnight. The product yield was 75%. Powder X-raydiffraction pattern of the product (FIG. 7, pattern B) shows asignificant decrease of all peaks characteristic of lamellar structureof MCM-22 (P), in agreement with the literature results.

Synthesis of UCB-1 via delamination of MCM-22(P). As-made MCM-22 (P)(1.00 g) was added to a mixture of cetyltrimethylammonium bromide (1.92g), tetrabutylammonium fluoride (Fluka, >90%, 1.92 g) andtetrabutylammonium chloride (Sigma Aldrich, 1.68 g) in deionized water(25.9 g). pH of the slurry was adjusted to approximately 9 by adding 40%tetrapropylammonium hydroxide solution, and the slurry was heated at 353K (80° C.) for 16 hours. After cooling the mixture, pH of the mixturewas adjusted to approximately 2 by adding concentrated HCl aqueoussolution in a fume hood. The mixture was transferred to a centrifugebottle with screw cap, and quickly centrifuged to separate a solid froma solution. The supernatant solution was discarded carefully, and theremaining solid was dried at 313 K (40° C.) overnight in the fume hood.The product yield was 90%.

Characterization. Powder X-ray diffraction (XRD) patterns were collectedon Siemens D5000 diffractometer using a Cu Kα radiation. See FIG. 7C.Transmission electron microscopy images were recorded on a Tecnai 20 ora JEOL JEM-2010 (200 kV). See FIGS. 10C and D. Nitrogen gas adsorptionwas measured on a Micromeritics ASAP2020 at 77 K (-194° C.). Prior tomeasurement, samples were evacuated at 623 K (350° C.) for 4 hours. SeeFIG. 8. ²⁹ 5 i solid-state MAS NMR spectra were measured using a BrukerAvance 500 MHz spectrometer with a wide bore 11.7 T magnet and employinga Bruker 4 mm MAS probe. The spectral frequencies were 500.23 MHz forthe ¹H nucleus and 99.4 MHz for the ²⁹Si nucleus. ²⁹Si MAS NMR spectrawere acquired after a 4 μs-90 degree pulse with application of a strong¹H decoupling pulse. The spinning rate was 12 kHz, and the recycle delaytime was 300 s. NMR shifts were reported in parts per million (ppm) whenexternally referenced to tetramethylsilane (TMS). See FIG. 6C. Mercuryporosimetry was conducted according to Standard Test Method forDetermining Pore Volume Distribution of Catalysts by Mercury IntrusionProlosimetry (ASTM D 428). See FIG. 9, curve 3.

EXAMPLE 2

Delamination of MCM-22 (P) without Chloride. Delamination of MCM-22 (P)was attempted under similar conditions to those described above, exceptwithout tetrabutylammonium chloride and with twice as much astetrabutylammonioum fluoride. The delamination was not successful. SeeFIG. 1.

EXAMPLE 3

Synthesis of ERB-l. ERB-1 was synthesized by the literature method.(Millini, et al., Microporous Materials, (1995) v. 4, p. 221). Sodiumhydroxide (EMD Chemicals, 97%, 0.653 g) and piperidine (Sigma Aldrich,99%, 6.360 g) were dissolved into deionized water (16.228 g). Boric acid(J.T. Baker, 4.396 g) was added to the mixture, and the whole mixturewas stirred at 323 K until the boric acid was completely dissolved.After cooling down the solution to room temperature, fumed silica (SigmaAldrich, 3.300 g) was added gradually over 1 hour. The whole mixture wasstirred for an additional 5 h, and divided into half. Each gel wastransferred into a Teflon-lined autoclave (Parr instrument, 23 mL). Eachreactor was tightly sealed and heated in a convection oven at 448 K for7 days with tumbling of the reactor. After 7 days of heating, thereactors were cooled down to room temperature, and the product wasseparated by centrifugation. The separated product was washed withdeionized water thoroughly, and finally dried at 313 K overnight. Thepowder X-ray diffraction (PXRD) pattern characterizing the synthesizedERB-I (pattern A in FIG. 12) matches literature data showing the 001 and002 diffraction peaks at 3.4° and 6.8°, respectively. These peaksrepresent a lamellar structure of ERB-1.

Delamination of as-made ERB-1 via Fluoride/Chloride Anion-PromotedExfoliation. As-made ERB-1 (0.381 g) was added to a mixture ofcetyltrimethylammonium bromide (Sigma Aldrich, 2.192 g),tetrabutylammonium fluoride (Fluka, ≧90%, 0.761 g) andtetrabutylammonium chloride (Sigma Aldrich, 0.638 g) in deionized water(15.51 g). The pH of the slurry was adjusted to approximately 9 byadding 40% tetrapropylammonium hydroxide solution, and the slurry washeated at 353 K for 16 hours. After cooling the mixture, the pH of themixture was adjusted to approximately 2 by adding concentrated HCIaqueous solution in a fume hood. The mixture was transferred to acentrifuge bottle with screw cap, and quickly centrifuged to separatethe solids. The supernatant solution was discarded, and the solid wasdried at 313 K (40° C.) overnight. The product was then characterized asin Example 1. See FIG. 12, pattern B.

EXAMPLE 4

Materials. All reagents used in zeolite synthesis and delamination wereof reagent-grade quality and were used as received.

Synthesis of PREFER. A typical synthesis of PREFER was made by mixing1.60 g fumed silica with 0.38 g alumina (bohemite, Catapal B). A mixtureof 1.47 g NH₄F and 0.50 g HF (49%) was added subsequently and the highlyviscous gel was stirred using a spatula until homogenous. A mixture of4.16 g 4-amino-2,2,6,6-tetramethylpiperidine

(Aldrich, 98%) and 4.43 g H₂O (Deionized) was added and the gel wasstirred until homogenous. The gel was transferred to a 25 mL teflonlined Parr stainless steel autoclave and heated at 175 ° C. for 5 daysin a tumbling oven at 60 rpm. FIG. 16 is a scanning electron microscopyimage characterizing PREFER.

Synthesis of UCB-2 via delamination of PREFER. PREFER was swollen bymixing 10.00 g dimethyl formamide (DMF), 0.85 g cetyltrimethyl-ammoniumbromide (CTAB), 0.85 g tetrabutylammonium fluoride (TBAF), 0.85 gtetrabutyl-ammonium chloride (TBAC1) and 0.50 g PREFER in a 25 mL teflonlined Parr stainless steel autoclave. The mixture was heated for 16hours at 100 ° C. in a tumbling oven at 60 rpm. After swelling,approximately 20 drops of concentrated HCl aq. was added and the productwas recovered by filtration through a fine glass filter. FIG. 17 is asolid state ²⁷Al MAS NMR spectra characterizing the as-made UCB-2.

Delamination of PREFER without Chloride. Delamination of PREFER wasattempted under similar conditions to those described above, exceptwithout tetrabutylammonium chloride and with twice as much astetrabutylammonium fluoride. In the absence of chloride, PREFER isswollen. This is indicated by the disappearance of the 200 peak andappearance of three new peaks in the PXRD pattern. However, addition ofHCl to the slurry leads to the complete disappearance of these new peaksand appearance of peaks resembling calcined PREFER. These resultsindicate that absence of chloride results in the condensation of layersupon acidification and does not result in delamination.

Delamination of PREFER without Fluoride. Delamination of PREFER wasattempted under similar conditions to those described above, exceptwithout tetrabutylammonium fluoride and with twice as much astetrabutylammonium chloride. Treating PREFER with DMF in the absence offluoride results in a lack of PREFER swelling. This result shows thatfluoride is a necessary component for delamination.

Reversibility test between swelling and delamination. To test whetherthe acidification step leads to irreversible condensation of the layers,the delaminated UCB-2 was washed thoroughly in water 5 times andsubjected to a new delamination process with CTAB, TBAF and TBAC1. Theobjective was to see if this treatment is able to swell the material.0.50 g washed UCB-2 was mixed with 0.85 g CTAB, 0.85 g TBAF, and 0.85 gTBAC1, and 10.00 g DMF in a 25 mL teflon lined Parr stainless steelautoclave. The mixture was heated for 16 hours at 100° C. in a tumblingoven at 60 rpm. FIG. 18 shows powder XRD patterns characterizing swollenPREFER in DMF, acidified PREFER and the material formed by swelling theacidified PREFER.

Characterization. Powder X-ray diffraction (XRD) patterns were collectedon a Bruker D8 Advance diffractometer using a Cu Ka radiation.Transmission electron microscopy images were recorded on a JEOL JEM-2010(200 kV). Argon gas adsorption isotherms were measured on aMicromeritics ASAP2020 at 86 K. Prior to measurement, samples wereevacuated at 623 K for 4 h. ²⁹Si solid-state MAS NMR spectra weremeasured using a Bruker Avance 500 MHz spectrometer with a wide bore11.7 T magnet and employing a Bruker 4 mm MAS probe. The spectralfrequencies were 500.23 MHz for the 1H nucleus and 99.4 MHz for the ²⁹Sinucleus. ²⁹Si MAS NMRspectra were acquired after a 4 μs-90 degree pulsewith application of a strong ¹H decoupling pulse. The spinning rate was12 kHz, and the recycle delay time was 300 s.

EXAMPLE 5

Synthesis and characterization of UCB-3 via delamination of PREFER

A mixture of PREFER (0.20 g), cetyltrimethylammonium bromide (CTAB, 0.22g), tetrabutylammonium fluoride (TBAF, 0.34 g), tetrabutylammoniumchloride (TBAC1, 0.34 g) in N,N-dimethyl formamide (4 mL) was heated ina sealed PFA tube at 373 K for 16 h. After 16 h of heating, the mixturewas cooled to room temperature, and the solid was separated byfiltration. The solid was extensively washed with deionized water, anddried at 323 K overnight. The synthesized material is designated asUCB-3. An advantage of this synthesis procedure relative to UCB-2, whichalso results from PREFER delamination, is that neither an acidificationstep nor acid are required.

Powder XRD (PXRD) characterizing UCB-3 shown in FIG. 19 showssignificant decrease and broadening of 200 peak (6.8°, 13 Å) as comparedwith that of PREFER (FIG. 19) as PREFER is delaminated by the treatment.

Argon gas physisorption isotherms of calcined materials are shown inFIG. 20. Table 2 represent micropore volumes, external surface area, andtotal pore volumes. Comparison of these results shows a significantdecrease in the micropore volume of UCB-3, along with an increase in theexternal surface area, relative to calcined PREFER, as expected fordelamination of PREFER layers.

TABLE 2 Results from argon gas adsorption experiments of calcined PREFERand UCB-3 micropore volume total pore volume S_(ext) Sample (cm³/g)(cm³/g) (m²/g) Calcined PREFER 0.07 0.13 18 Calcined UCB-3 0.006 0.25152

EXAMPLE 6 Synthesis and Characterization of UCB-4 via Delamination ofPREFER

A mixture of PREFER (0.20 g), cetyltrimethylammonium bromide (CTAB, 0.22g), tetrabutylammonium fluoride (TBAF, 0.34 g), tetrabutylammoniumchloride (TBAC1, 0.34 g) in N,N-dimethyl formamide (4 mL) was heated ina sealed PFA tube at 373 K for 16 h. After cooled to room temperature,the slurry was subjected to sonication in an ice bath for 1 h. Then, thesolid was separated by filtration, and washed with about 50 mL of DMF.After separation by filtration, the solid was dried at 323 K overnight.The synthesized material is designated as UCB-4. This synthesis, likethat of UCB-3, obviates the need for acidification and acid use, though,unlike UCB-3, it involves sonication.

Powder XRD (PXRD) characterizing UCB-4 shown in FIG. 21 showsdisappearance of 200 peak (6.8°, 13 Å) as compared with that of PREFER(FIG. 21) following the treatment described above. A distinctiveadvantage of UCB-4 relative to UCB-3 is a higher extent of delamination,as indicated by the complete absence of the (200) peak in FIG. 21 (i.e.compare with intensity of this broad peak in FIG. 19). Argon gasphysisorption of calcined materials are shown in FIG. 22. UCB-4 consistsof a micropore volume that is less than 0.001 cm³/g, an external surfacearea of 171 m²/g, and a total pore volume of 0.51 cm³/g.

Comparison of these results with those of calcined PREFER as well ascalcined UCB-3 shows a significant decrease in the micropore volume ofUCB-4 and an increase in the external surface area, relative to bothPREFER and UCB-3. These data are consistent with PREFER delamination inUCB-4, and an even greater degree of PREFER delamination in UCB-4 thanin UCB-3.

EXAMPLE 7 Synthesis of Al-SSZ-70

A gel consisting of aluminum hydroxide (53wt % as Al2O3, 0.171 g),distilled water (6.88 g), diisobutylimidazolium hydroxide solution (0.50mmol/g, 35.6 g), sodium hydroxide solution (1N, 8.89 g), and fumedsilica (5.50 g) was divided into four portions. Each gel was heated in a23-mL Teflon-lined autoclave at 423 K with tumbling for 11 days. Afterthe reaction mixtures were cooled down to room temperature, and thesolid was separated by filtration, and subsequently washed withdistilled water. The solid was dried at 353 K overnight.

Synthesis and Characterization of UCB-5 via Delamination of Al-SSZ-70

A mixture of Al-SSZ-70 (0.20 g), cetyltrimethylammonium bromide (CTAB,0.22 g), tetrabutylammonium fluoride (TBAF, 0.34 g), tetrabutylammoniumchloride (TBAC1, 0.34 g) in N,N-dimethyl formamide (4 mL) was heated ina sealed PFA tube at 373 K for 16 h. After cooling to room temperature,the slurry was subjected to sonication in an ice bath for 1 h. Then, thesolid was separated by filtration, and washed with about 50 mL of DMF.After separation by filtration, the solid was dried at 323 K overnight.The synthesized material is designated as UCB-5.

Powder XRD (PXRD) characterizing as-made Al-SSZ-70 and UCB-5 are shownin FIG. 23. The pattern characterizing Al-SSZ-70 (FIG. 23 a) shows apeak at 6.6° (13.4 Å) that represents the lamellar structure of thismaterial. The pattern for UCB-5 (FIG. 23 b) shows complete disappearanceof this peak, as layers in Al-SSZ-70 have become delaminated.

Argon gas physisorption data of calcined materials are shown in FIG. 24.Table 3 summarizes corresponding micropore volumes, external surfacearea, and total pore volumes. Comparison of these results shows asignificant decrease in the micropore volume for UCB-5, along with anincrease in the external surface area, as expected for delamination ofAl-SSZ-70 layers.

TABLE 3 Results from argon gas adsorption experiments of calcinedAl-SSZ-70 and UCB-5 micropore volume total pore volume Sext Sample(cm3/g) (cm3/g) (m2/g) calcined Al-SSZ-70 0.16 0.33 89 calcined UCB-50.10 0.35 135

EXAMPLE 8

Synthesis of B-SSZ-70

A gel consisting of boric acid (0.172 g), distilled water (2.52 g),diisobutylimidazolium hydroxide solution (0.48 mmol/g, 17.7 g), sodiumhydroxide solution (1N, 4.20 g), and fumed silica (2.60 g) was dividedinto two portions. Each gel was heated in a 23-mL Teflon-lined autoclaveat 423 K with tumbling for 17 days. After the reaction mixtures werecooled down to room temperature, and the solid was separated byfiltration, and subsequently washed with distilled water. The solid wasdried at 353 K overnight.

Synthesis and Characterization of UCB-6 via Delamination of B-SSZ-70

A mixture of B-SSZ-70 (0.20 g), cetyltrimethylammonium bromide (CTAB,0.22 g), tetrabutylammonium fluoride (TBAF, 0.34 g), tetrabutylammoniumchloride (TBACl, 0.34 g) in N,N-dimethyl formamide (4 mL) was heated ina sealed PFA tube at 373 K for 16 h. After cooled to room temperature,the slurry was subjected to sonication in an ice bath for 1 h. Then, thesolid was separated by filtration, and washed with about 50 mL of DMF.After separation by filtration, the solid was dried at 323 K overnight.The synthesized material is designated as UCB-6.

Powder XRD (PXRD) characterizing as-made B-SSZ-70 and UCB-6 are shown inFIG. 25. The pattern characterizing B-SSZ-70 (FIG. 25 a) shows a peak at6.6° (13.4 Å) that represent lamellar structure of this material. Thepattern for UCB-6 (FIG. 25 b) shows a significant decrease andbroadening of this peak, consistent with delaminated B-SSZ-70 layers.

Argon gas physisorption data of calcined materials are shown in FIG. 26.Table 4 summarizes corresponding micropore volumes, external surfacearea, and total pore volumes. Comparison of these results shows asignificant decrease in the micropore volume for UCB-6, along with anincrease in the external surface area, as expected for delamination ofB-SSZ-70 layers.

TABLE 4 Results from argon gas adsorption experiments of calcinedB-SSZ-70 and UCB-6 micropore volume total pore volume Sext Sample(cm3/g) (cm3/g) (m2/g) calcined B-SSZ-70 0.15 0.34 74 calcined UCB-60.06 0.30 105

Approximately 30 mg of UCB-1 was calcined at 550 ° C. for 2 h in flowingdry nitrogen in thermogravimetric analyzer (TA Instruments, modelTA2920). After cooling the calcined UCB-1 down to 150° C. under the samedry nitrogen stream, 50 μL of pyridine base probe molecule was injectedinto the inlet gas flow line via syringe. The probe molecule adsorbed onacid sites of UCB-1. After the temperature was kept at 150° C. for 30 h,the temperature of the sample was ramped up to 250 ° C. and held therefor 2 h. Then, the temperature of the sample was ramped up to 350 ° C.and held there for 2 h. The same set of experiments was conducted withbulky pyridines such as 2,6-di-tert-butylpyridine (DTBP) and collidine.

FIG. 27 shows chemisorbed amounts of base molecules at 150-350° C. Theresults show that approximately 30-45% of acid sites accessible topyridine are also accessible to DTBP or collidine. This large fractionof either DTBP- or collidine-accessible sites is due to the largefraction of acid sites near the external surface, as a result ofdelaminated layers in UCB-1.

All patents and publications referenced herein are hereby incorporatedby reference to the extent not inconsistent herewith. It will beunderstood that certain of the above-described structures, functions,and operations of the above-described embodiments are not necessary topractice the present invention and are included in the descriptionsimply for completeness of an exemplary embodiment or embodiments. Inaddition, it will be understood that specific structures, functions, andoperations set forth in the above-described referenced patents andpublications can be practiced in conjunction with the present invention,but they are not essential to its practice. It is therefore to beunderstood that the invention may be practiced otherwise than asspecifically described without actually departing from the spirit andscope of the present invention as defined by the appended claims.

1. A method of preparing an exfoliated layered zeolite precursormaterial comprising preparing an aqueous mixture of chloride andfluoride anions and a layered oxide material to be delaminated,maintaining the aqueous mixture at a pH of 12 or less at a temperaturein the range of 5-150° C. for a length of time sufficient to effect thedesired delamination, and then recovering the exfoliated layered zeoliteprecursor material.
 2. The method of claim 1, wherein the layeredzeolite precursor oxide material to be delaminated is selected from thegroup consisting of SSZ-25, ERB-1, PREFER, SSZ-70, Nu-6(1), and MCM-22(P).
 3. The method of claim 1, wherein the layered oxide material to bedelaminated is MCM-22 (P).
 4. The method of claim 1, wherein the layeredoxide material to be delaminated is ERB-1.
 5. The method of claim 1,wherein the aqueous mixture of chloride and fluoride anions comprises amixture of an alkylammonium fluoride and chloride.
 6. The method ofclaim 1, wherein bromide anions are also present in the aqueous mixture.7. The method of claim 6, wherein the aqueous mixture comprises analkylammonium bromide.
 8. The method of claim 5, wherein thealkylammonium fluoride and chloride compounds are tetrabutylammoniumcompounds.
 9. The method of claim 7, wherein the alkylammonium bromidecompound is cetyltrimethylammonium bromide.
 10. The method of claim 1,wherein the pH is 11 or less.
 11. The method of claim 1, wherein the pHis 9 or less.
 12. The method of claim 1, wherein the temperature is inthe range of about 50-100° C.
 13. The method of claim 1, wherein theaqueous mixture is maintained for a period of time ranging from about 30minutes to one month.
 14. The method of claim 1, wherein the aqueousmixture is maintained for a period of time ranging from about 2 to 50hours.
 15. The method of claim 1, wherein the zeolite precursor layeredoxide material to be delaminated is MCM--22 (P), the aqueous mixturecomprises tetrabutylammonium fluoride, tetrabutylammonium chloride andcetyltrimethylammonium bromide, the pH is about 9, the temperature isabout 80° C. and the aqueous mixture is maintained for about 5-20 hoursprior to collection of the product exfoliated layered zeolite precursormaterial.
 16. The method of claim 1, wherein the product exfoliatedlayered zeolite precursor material recovered is UCB-1.
 17. The method ofclaim 1, wherein the aqueous mixture is acidified prior to recoveringthe product.
 18. A method of preparing a delaminated layered precursormaterial using an aqueous mixture of chloride and fluoride anions in theabsence of sonication.
 19. The method of claim 1, wherein the molarratio of chloride to fluoride anions in the aqueous mixture is from100:1 to 1:100.